[Haskell-cafe] where to put general-purpose utility functions
jgoerzen at complete.org
Thu Jan 26 02:23:05 CET 2012
Apologies for such a late reply. I don't know if others have replied on
-cafe; it has become too high-volume for me to follow of late. There
are several options. MissingH is one. I have accepted patches there
for a long time. Another is that now that Hackage/Cabal foster easy
inclusion of small packages, you might want to roll your own.
(Occasionally I have hesitation about drive-by commits to MissingH
because I get asked to support the code later at times.)
On 01/21/2012 02:20 PM, Joey Hess wrote:
> I'm finding a rather unusual problem as I write haskell..
> Unlike every other language I've used, large portions of my haskell code
> are turning out to be general-purpose, reusable code. Fully 20% of the
> haskell code I've written for git-annex is general purpose. Now, I came out
> of a decade of perl with maybe 1% reusable code. So I'm sure this is a
> credit to haskell, and not to me.
> My problem now is that as I start new projects, I want to have my haskell
> utility functions available, and copying them around is not ideal. So, put
> them on hackage. But where, exactly? It already has several grab bag utility
> libraries. The only one with much traction is MissingH. Using the others
> makes a program have an unusual dependency, which while only a cabal
> install away, would make work for distributions that want to package the
> program. I've ruled out using a couple on that basis. Doesn't encourage me
> to add another one.
> My 2000+ lines of reusable code are a grab-bag of generic utility
> functions. Looking them over (see Appendix), I could try to get portions
> into existing libraries on hackage, but it's unlikely I'd find a home
> for most of them, so I'm still left with this problem of what to do.
> I wonder if the model used for xmonad-contrib, of a big library package,
> that is very open to additions from contributors, would be helpful here?
> John, any interest in moving MissingH in this direction? I get the
> impression it's not otherwise changing much lately, and parts of it are
> becoming naturally obsolete, maybe this could inject some life into it.
> Any other thoughts you have on grab-bag utility libraries on hackage
> also appreciated.
> Appendix: A sample of a a few of the better functions from my utility library.
> Some quite generic monadic control functions, few of them truely unique:
> whenM :: Monad m => m Bool -> m () -> m () -- also>>?
> unlessM :: Monad m => m Bool -> m () -> m () -- also>>!
> firstM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)
> A module that exports functions conflicting with partial
> functions in the Prelude, to avoid them being accidentially
> used. And provides some alternatives (which overlap somewhat with Safe):
> headMaybe :: [a] -> Maybe a
> readMaybe :: Read a => String -> Maybe a
> beginning :: [a] -> [a]
> Various path manipulation functions such as:
> dirContains :: FilePath -> FilePath -> Bool
> dotfile :: FilePath -> Bool
> absPath :: FilePath -> IO FilePath
> Other stuff:
> separate :: (a -> Bool) -> [a] -> ([a], [a])
> catchMaybeIO :: IO a -> IO (Maybe a)
> readSize :: [Unit] -> String -> Maybe ByteSize -- parses "100 kb" etc
> format :: Format -> Variables -> String
> findPubKeys :: String -> IO GpgKeyIds
> boolSystem :: FilePath -> [CommandParam] -> IO Bool
> withTempFile :: Template -> (FilePath -> Handle -> IO a) -> IO a
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